Pyroelectric detector, pyroelectric detection device, and electronic instrument

ABSTRACT

A pyroelectric detector includes a pyroelectric detection element mounted on a first side of a support member with a second side facing a cavity. The pyroelectric detection element has a capacitor including a first electrode, a pyroelectric body and a second electrode, and an interlayer insulation layer forming first and second contact holes passing respectively through to the first and second electrodes. First and second plugs are respectively embedded in the first and second contact holes, with first and second electrode wiring layers are respectively connected to the first and second plugs. A thermal conductivity of material of the second electrode wiring layer is lower than a thermal conductivity of material of a portion of the second electrode connected to the second plug.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2010-144897 filed on Jun. 25, 2010. The entire disclosure of JapanesePatent Application No. 2010-144897 is hereby incorporated herein byreference.

BACKGROUND

1. Technical Field

The present invention relates to a pyroelectric detector, a pyroelectricdetection device, and an electronic instrument or the like.

2. Related Art

Known pyroelectric detection devices include pyroelectric orbolometer-type infrared detection devices. An infrared detection deviceutilizes a change (pyroelectric effect or pyroelectronic effect) in theamount of spontaneous polarization of a pyroelectric body according tothe light intensity (temperature) of received infrared rays to create anelectromotive force (charge due to polarization) at both ends of thepyroelectric body (pyroelectric-type) or vary a resistance valueaccording to the temperature (bolometer-type) and detect the infraredrays. Compared with a bolometer-type infrared detection device, apyroelectric infrared detection device is complex to manufacture, buthas the advantage of excellent detection sensitivity.

A cell of a pyroelectric infrared detection device has an infrareddetection element which includes a capacitor composed of a pyroelectricbody connected to an upper electrode and a lower electrode, and variousproposals have been made regarding the electrode wiring structure or thematerial of the electrodes or the pyroelectric body (Japanese Laid-OpenPatent Application Publication No. 10-104062 and Japanese Laid-OpenPatent Application Publication No. 2008-232896).

A capacitor which includes a ferroelectric body connected to an upperelectrode and a lower electrode is used in ferroelectric memory, andvarious proposals have been made regarding the material of theelectrodes or the ferroelectric body to be suitable for ferroelectricmemory (Japanese Laid-Open Patent Application Publication No. 2009-71242and Japanese Laid-Open Patent Application Publication No. 2009-129972).

SUMMARY

In Japanese Laid-Open Patent Application Publication No. 10-104062, thelower electrode as such is extended so as to serve also as a lowerelectrode wiring, and the upper electrode as such is extended so as toserve also as an upper electrode wiring layer. A material having lowelectrical resistance (e.g., Pt, Ir, or the like) is used for the lowerelectrode and upper electrode of the capacitor in order to obtain thedesired electrical characteristics, and the thermal conductivity thereofis also high (71.6 W/m·K for Pt, and 147 W/m·K for Ir). The heat of theinfrared detection element is therefore transmitted to the outside viathe lower electrode wiring or the upper electrode wiring in thetechnique of Japanese Laid-Open Patent Application Publication No.10-104062. High characteristics therefore cannot be ensured in apyroelectric infrared detector that operates according to a detectionprinciple in which the amount of polarization of the pyroelectric bodychanges based on temperature.

As a modification of the technique of Japanese Laid-Open PatentApplication Publication No. 10-104062, a stack configuration in which alower electrode wiring layer is connected to a lower surface of thelower electrode, and an upper electrode wiring is connected to an uppersurface of the upper electrode is used in ferroelectric memory.

In Japanese Laid-Open Patent Application Publication No. 2008-232896, aplanar-type capacitor is developed which differs from that of thispublication. In Japanese Laid-Open Patent Application Publication No.2008-232896, a lower platinum layer (8) as a lower metal thin layer isformed on an Al₂O₃ thin layer (6) having crystalline properties which isformed on a single-crystal semiconductor substrate (4), a ferroelectricthin layer (10) is laminated on only a portion of an upper surface ofthe lower metal thin layer (8), and an upper platinum layer (12) as anupper metal thin layer is laminated on only a portion of an uppersurface of the ferroelectric thin layer (8) (FIGS. 2 and 3, and Claim1). Wiring (16) formed by a metal thin layer is connected to an exposedpart not covered by an insulation layer (14) on the lower metal thinlayer (8) and an upper surface of the upper metal thin layer (12)(Paragraph 0033).

However, Japanese Laid-Open Patent Application Publication No.2008-232896 is concerned solely with the crystalline properties of thelower metal thin layer (8), the ferroelectric thin layer (10), and theupper metal thin layer (12), and is not concerned with protecting thecapacitor from reducing gas, or with the dissipation of heat from thewiring (16).

An object of the several aspects of the present invention is to providea pyroelectric detector, a pyroelectric detection device, and anelectronic instrument whereby high detection characteristics can berealized while suppressing the dissipation of heat through the wiringfrom the pyroelectric detection element, in view of a detectionprinciple in which the amount of polarization of a pyroelectric bodychanges based on temperature.

A pyroelectric detector according to one aspect of the present inventionis includes a support member and a pyroelectric detection element. Thesupport member includes a first side and a second side opposite from thefirst side, with the second side facing a cavity. The pyroelectricdetection element is mounted on the first side of the support member.The pyroelectric detection element includes a capacitor, an interlayerinsulation layer, a first plug, a second plug, a first electrode wiringlayer, and a second electrode wiring layer. The capacitor includes afirst electrode, a pyroelectric body and a second electrode, the firstelectrode being mounted on the support member and including a firstregion in which the pyroelectric body is disposed and a second regionextending from the first region. The pyroelectric body is disposed overthe first electrode in the first region, and the second electrode beingdisposed over the pyroelectric body. The interlayer insulation layercovers a surface of the capacitor, and forms a first contact holepassing through to the first electrode in the second region, and asecond contact hole passing through to the second electrode. The firstplug is embedded in the first contact hole. The second plug is embeddedin the second contact hole. The first electrode wiring layer is formedon the interlayer insulation layer and on the first side of the supportmember, and connected to the first plug. The second electrode wiringlayer is formed on the interlayer insulation layer and on the first sideof the support member, and connected to the second plug. The thermalconductivity of material of the second electrode wiring layer is lowerthan a thermal conductivity of material of a portion of the secondelectrode connected to the second plug.

Through this aspect of the present invention, by adopting a planar-typecapacitor structure, the drawbacks of the stack-type capacitor structureare overcome, and the sensor characteristics can be enhanced. Althoughthe second electrode wiring layer connected to the pyroelectric body viathe second plug and the second electrode is indispensible for drivingthe capacitor, the second electrode wiring simultaneously functions as aradiation path. In an aspect of the present invention, by making thethermal conductivity of the second electrode wiring layer lower thanthat of the second electrode, the radiation of heat from thepyroelectric body can be suppressed, and the thermal separationproperties of the infrared detection element are enhanced.

In the pyroelectric detector as described above, a thermal conductivityof material of the first electrode wiring layer is preferably lower thana thermal conductivity of material of a portion of the first electrodeconnected to the first plug.

The first electrode wiring layer connected to the pyroelectric body viathe first plug and the first electrode is also indispensible for drivingthe capacitor, but the first electrode wiring simultaneously functionsas a radiation path. In an aspect of the present invention, by makingthe thermal conductivity of the first electrode wiring layer lower thanthat of the first electrode, the radiation of heat from the pyroelectricbody can be suppressed, and the thermal separation properties of theinfrared detection element are enhanced.

In the pyroelectric detector as described above, at least one of thefirst electrode wiring layer and the second electrode wiring layerpreferably contains one of titanium nitride and titanium aluminumnitride.

The thermal conductivity of titanium nitride or titanium aluminumnitride is adequately smaller than that of the metal suitable for thefirst and second electrode material, e.g., platinum or iridium.

In the pyroelectric detector as described above, a thermal conductanceof the second electrode is preferably greater than a thermal conductanceof the first electrode. Since the first electrode directly touches thesupport member and diffuses heat by solid conduction, the thermalconductance of the first electrode is preferably low. On the other hand,since the second electrode does not directly touch the support memberand other components, the thermal conductance of the second electrodemay be greater than that of the first electrode. Even in this case,dissipation of heat from the side of the second electrode can besuppressed by reducing the thermal conductivity of the second electrodewiring layer.

In the pyroelectric detector as described above, the pyroelectricdetection element further preferably includes a light-absorbing memberdisposed in a region further upstream in a light incidence directionthan the second electrode and the second electrode wiring layer.

When the light-absorbing member is disposed further upstream in thelight incidence direction than the capacitor, the heat due to lightirradiation is transferred to the pyroelectric body from thelight-absorbing member. Since the second electrode is present in thisthermal conduction path, the suppression of radiation from the secondelectrode wiring layer connected to the second electrode contributes toincreasing the efficiency of heat transfer from the light-absorbingmember to the pyroelectric body. The thermal separation properties ofthe infrared detection element can be enhanced by merely reducing thethermal conductivity of the second electrode wiring layer to a valuebelow that of the second electrode.

In the pyroelectric detector as described above, the light-absorbingmember preferably covers an entire surface of the second electrode inplan view as viewed along the light incidence direction, and the secondelectrode preferably covers an entire surface of a first side of thepyroelectric body that is opposite from a second side facing the firstelectrode.

Through this configuration, the entire surface of the second electrodecan be used as a light-reflecting surface, and the light absorptionefficiency is improved by causing the light transmitted by thelight-absorbing member to return to the light-absorbing member.

In the pyroelectric detector as described above, the light-absorbingmember preferably overlaps with the first region of the first electrodeand at least a portion of the second region of the first electrode inplan view as viewed along the light incidence direction.

Through this configuration, the volume of the light-absorbing member isincreased, the amount of light absorption is increased, and the firstelectrode can also be used as a light-reflecting surface. The lightabsorption efficiency can also be further improved by causing the lighttransmitted by the light-absorbing member to return to thelight-absorbing member.

In the pyroelectric detector as described above, the first electrodewiring layer preferably includes a first connecting part connected tothe first plug, and a first lead wiring part extending from the firstconnecting part and having a width smaller than a width of the firstconnecting part, the second electrode wiring layer preferably includes asecond connecting part connected to the second plug, and a second leadwiring part extending from the second connecting part and having a widthsmaller than a width of the second connecting part, and the width of thesecond lead wiring part is preferably less than a maximum length in atransverse-cross section of the second contact hole.

Through this configuration, the thermal resistance of the second leadwiring part is increased, the thermal separation properties of thepyroelectric detection element are enhanced, the amount of lightreflected by the second lead wiring part is reduced, the amount of lightreflected by the second electrode can be increased, and the lightabsorption efficiency increases.

In the pyroelectric detector as described above, the width of the firstlead wiring part is preferably less than the maximum length in atransverse cross-section of the first contact hole.

Through this configuration, the thermal resistance of the first leadwiring part is increased, the thermal separation properties of thepyroelectric detection element are enhanced, the amount of lightreflected by the first lead wiring part is reduced, the amount of lightreflected by the first electrode can be increased, and the lightabsorption efficiency increases.

In the pyroelectric detector as described above, a reducing gas barrierlayer is preferably further provided between the interlayer insulationlayer and the capacitor.

The characteristics of the capacitor degrade when oxygen deficit occursdue to reducing gas during manufacturing or use of the capacitor, butthe capacitor can be protected by the reducing gas barrier layer.

A pyroelectric detection device according to another aspect of thepresent invention includes a plurality of the pyroelectric detectorsdescribed above, arranged in two dimensions along two axes. In thispyroelectric detection device, the detection sensitivity is increased inthe pyroelectric detector of each cell, and a distinct light(temperature) distribution image can therefore be provided.

An electronic instrument according to another aspect of the presentinvention has the pyroelectric detector or the pyroelectric detectiondevice described above. By using one or a plurality of cells of thepyroelectric detector as a sensor, the electronic instrument is mostsuitable in thermography for outputting a light (temperature)distribution image, in automobile navigation or surveillance cameras aswell as object analysis instruments (measurement instruments) foranalyzing (measuring) physical information of objects, in securityinstruments for detecting fire or heat, in FA (Factory Automation)instruments provided in factories or the like, and in otherapplications. The pyroelectric detector or pyroelectric detectiondevice, or the electronic instrument having the pyroelectric detector orpyroelectric detection device, may also be applied in a flow sensor orthe like for detecting the flow rate of a liquid under conditions inwhich an amount of supplied heat and an amount of heat taken in by thefluid are in equilibrium. The pyroelectric detector or pyroelectricdetection device of the present invention may be provided in place of athermocouple or the like provided to the flow sensor, and a subjectother than light may be detected.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a simplified sectional view showing the planar-type capacitoraccording to an embodiment of the present invention;

FIG. 2 is a simplified plan view showing the pyroelectric infrareddetection device according to an embodiment of the present invention;

FIG. 3 is a simplified sectional view showing the pyroelectric detectorof one cell of the pyroelectric infrared detection device according toan embodiment of the present invention;

FIG. 4 is a simplified sectional view showing a manufacturing step, andshows the support member and infrared detection element formed on thesacrificial layer;

FIG. 5 is a simplified sectional view showing a modification in whichthe reducing gas barrier properties in the vicinity of the wiring plugare enhanced;

FIG. 6 is a simplified sectional view showing the capacitor structure ofthe pyroelectric infrared detector;

FIG. 7 is a simplified sectional view showing the pyroelectric infrareddetector in which the infrared-absorbing layer is disposed in adifferent region;

FIG. 8 is a block diagram showing the electronic instrument whichincludes the thermo-optical detector or thermo-optical detection device;

FIGS. 9A and 9B are views showing an example of the configuration of apyroelectric detection device in which pyroelectric detectors arearranged in two dimensions;

FIG. 10 is a sectional view showing an example of a stack-type capacitoras a comparative example; and

FIG. 11 is a sectional view showing another example of a stack-typecapacitor as a comparative example.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 1. Pyroelectric InfraredDetection Device

FIG. 2 shows a pyroelectric infrared detection device (one example of apyroelectric detection device) in which a plurality of cells ofpyroelectric infrared detectors 200 is arranged along two orthogonalaxes, each cell being provided with a support member 210 and apyroelectric detection element 220 mounted on the support member 210shown in FIG. 1. A pyroelectric infrared detection device may also beformed by a pyroelectric infrared detector of a single cell. In FIG. 2,a plurality of posts 104 is provided upright from a base part (alsoreferred to as a fixing part) 100, and pyroelectric infrared detectors200, each cell of which is supported by two posts 104, for example, arearranged along two orthogonal axes. The area occupied by each cell ofpyroelectric infrared detectors 200 is 30×30 μm, for example.

As shown in FIG. 2, each pyroelectric infrared detector 200 includes asupport member (membrane) 210 linked to two posts (support parts) 104,and an infrared detection element (one example of a pyroelectricdetection element) 220. The area occupied by the pyroelectric infrareddetection element 220 of one cell is 10×10 μm, for example.

Besides being connected to the two posts 104, the pyroelectric infrareddetector 200 of each cell is in a non-contacting state, a cavity 102(see FIG. 2) is formed below the pyroelectric infrared detector 200, andopen parts 102A communicated with the cavity 102 are provided on theperiphery of the pyroelectric infrared detector 200 in plan view. Thepyroelectric infrared detector 200 of each cell is thereby thermallyseparated from the base part 100 as well as from the pyroelectricinfrared detectors 200 of other cells.

The support member 210 has a mounting part 210A for mounting andsupporting the infrared detection element 220, and two arms 210B linkedto the mounting part 210A, and free end parts of the two arms 210B arelinked to the posts 104. The two arms 210B are formed so as to extendredundantly and with a narrow width in order to thermally separate thepyroelectric infrared detection element 220.

FIG. 2 is a plan view which omits the members above the wiring layersconnected to the upper electrodes, and FIG. 2 shows a first electrode(lower electrode) wiring layer 222 and a second electrode (upperelectrode) wiring layer 224 connected to the pyroelectric infrareddetection element 220. The first and second electrode wiring layers 222,224 extend along the arms 210B, and are connected to a circuit insidethe base part 100 via the posts 104. The first and second electrodewiring layers 222, 224 are also formed so as to extend redundantly andwith a narrow width in order to thermally separate the pyroelectricinfrared detection element 220.

2. Planar-Type Capacitor and Stack-Type Capacitor 2.1 Planar-TypeCapacitor

FIG. 1 shows a planar-type capacitor 230 used in the pyroelectricinfrared detector of the present embodiment. Stack-type capacitors areshown in FIGS. 10 and 11 as comparative examples.

In FIG. 1, the pyroelectric infrared detector includes the pyroelectricinfrared detection element 220 and the support member 210. The supportmember 210 includes a first surface 211A on a first side and a secondsurface 211B on a second side which is opposite from the first surface211A, with the pyroelectric infrared detection element 220 being mountedon the first surface 211A. The second surface 211B of the support member210 faces the cavity 102, and a portion of the support member 210 issupported by the posts (support parts) 104 shown in FIG. 2.

The capacitor 230 of the pyroelectric infrared detection element 220includes a first electrode (lower electrode) 234, a second electrode(upper electrode) 236, and a pyroelectric body 232 (pyroelectricmaterial) disposed between the first and second electrodes 234, 236, andthe infrared detection element 220 has a capacitor 230 in which anamount of polarization changes based on temperature. The first electrode234 includes a first region 233A in which the pyroelectric body 232 islaminated and formed, and a second region 233B which is formed so as toextend from the first region 233A. The first electrode 234 is mounted onthe support member 210, and the capacitor 230 is thereby supported.

An interlayer insulation layer 250 is formed so as to cover the surfaceof the capacitor 230. A first contact hole 252 is formed in theinterlayer insulation layer 250 so as to pass through the second region233B of the first electrode 234, and a second contact hole 254 is formedso as to pass through the second electrode 236.

A first plug 226 is formed so as to be embedded in the first contacthole 252. A first electrode wiring layer 222 connected to the first plug226 is formed on the interlayer insulation layer 250 and the supportmember 210. In the same manner, a second plug 228 is formed so as to beembedded in the second contact hole 254. A second electrode wiring layer224 connected to the second plug 228 is formed on the interlayerinsulation layer 250 and the support member 210.

2.2 Stack-Type Capacitor

Stack-type capacitors for comparison with the planar-type capacitor ofthe present embodiment are shown in FIGS. 10 and 11. In the stack-typecapacitors shown in FIGS. 10 and 11, the wiring structure with respectto the first electrode (lower electrode) 234 differs from that of theplanar-type capacitor shown in FIG. 1.

In FIG. 10, a contact hole 600 opening in the first surface 211A of thesupport member 210 is formed, a first electrode wiring layer 602 isformed inside the layer of the support member 210, and the firstelectrode 234 and the first electrode wiring layer 602 are connected bya plug 604 which is filled into the contact hole 600.

In this case, the first electrode wiring layer 602 is formed on anetching protection layer 606 (omitted in FIG. 1) formed on a lowersurface of the support member 210, and the support member 210 issubsequently laminated. As described in detail hereinafter, the etchingprotection layer 606 is a layer for protecting the support member 210from the etchant when the sacrificial layer is isotropically etched toform the cavity 102 after the support member 210 and other componentslaminated on the sacrificial layer are formed.

After the first electrode wiring layer 602 is formed on the etchingprotection layer 606, the first electrode wiring layer 602 is etched forpatterning. At this time, the etching protection layer 606 is etchedtogether with the first electrode wiring layer 602, and a portion havinga small layer thickness is formed, as shown in a partial enlarged view Bof FIG. 10. In the partial enlarged view B in FIG. 10, only the supportmember 210, the first electrode wiring layer 602 and the etchingprotection layer 606 are shown for the sake of brevity. The protectivelayer capability of the etching protection layer 606 decreases as thethickness thereof decreases. When the etching protection layer 606 isformed so as to have a large thickness in advance out of considerationfor this thin-film phenomenon, heat from the infrared detection element220 readily diffuses via the etching protection layer 606, and thethermal separation characteristics of the infrared detection element 220are degraded.

On the other hand, in the stack-type capacitor shown in FIG. 11, a firstelectrode wiring layer 608 which touches the first electrode 234 isformed on the uppermost layer of the support member 210. At this time,after the first electrode wiring layer 608 is formed on the entiresurface of the support member 210, the first electrode wiring layer 608is patterned. In this state, a level difference occurs, and after thesupport member 210 is additionally laminated, the surface of the supportmember 210 is smoothed so as to be flush with the first electrode wiringlayer 608. The first electrode 234, the pyroelectric body 232, and thesecond electrode 236 are subsequently laminated, and then patterned toform the shape of the capacitor 230. During patterning of the capacitor230, the first electrode wiring layer 608 in the region other than theregion directly below the first electrode 234 is etched so that thelayer thickness thereof is reduced, as shown in a partial enlarged viewC of FIG. 11, or a disconnection occurs. In the partial enlarged view Cin FIG. 11, only the support member 210, the first electrode wiringlayer 608 and the first electrode 234 are shown for the sake of brevity.Considering this phenomenon, even when the first electrode wiring layer608 is formed so as to have a large thickness, since the layer thicknessof the first electrode wiring layer 608 fluctuates due to etching, andthe thermal separation characteristics also fluctuate, the sensorcharacteristics are degraded.

2.3 Problems of Thermally Separated Pyroelectric Detector and Measuresfor Solving the Problems

From the perspective of the sensor characteristics of a thermallyseparated infrared detection element as described above, a planar-typecapacitor is superior to a stack-type capacitor. However, thefunctioning of the first and second electrode wiring layers as thermalconduction paths is a problem common to both a planar-type capacitor anda stack-type capacitor.

In other words, although the first and second electrode wiring layers222, 224 are indispensible for driving the pyroelectric capacitor 230,the heat of the capacitor 230 is radiated from the first and secondelectrode wiring layers 222, 224.

Therefore, in the present embodiment, a configuration is adopted inwhich the thermal conductivity of the material for forming the first andsecond electrode wiring layers 222, 224 is lower than the thermalconductivity of the material (single-layer electrode material in thecase of single-layer electrodes, and the electrode material of theuppermost layer in the case of multi-layer electrodes) for forming thefirst and second electrodes 234, 236 in the portions connected to thefirst and second plugs 226, 228.

The thermal conductivity of the material of the first and secondelectrodes 234, 236 is 71.6 W/m·K in the case of platinum (Pt), and 147W/m·K in the case of iridium (Ir), for example. On the other hand, thethermal conductivity of the common wiring materials aluminum (Al) andcopper (Cu) is 237 W/m·K and 403 W/m·K, respectively, which is usuallyhigher than that of the first and second electrodes 234, 236.

In the present embodiment, the first and second electrode wiring layers222, 224 are formed of titanium nitride (TiN) or titanium aluminumnitride (TiAlN), for example, as materials having lower thermalconductivity than platinum (Pt) or iridium (Ir), for example, which aremetal materials preferred as the electrode material of the first andsecond electrodes 234, 236. The thermal conductivity of titanium nitride(TiN), for example, is 29 W/m·K, and the thermal conductivity oftitanium aluminum nitride (TiAlN) is 5 to 10 W/m·K, which is adequatelylower than the thermal conductivity of platinum (Pt) or iridium (Ir),for example, which are the metal materials preferred as the electrodematerial of the first and second electrodes 234, 236.

Through this configuration, it is possible to suppress the radiation ofheat of the pyroelectric body 232 via the first and second electrodewiring layers 222, 224, which are indispensible for driving thecapacitor 230, and the thermal separation properties of the infrareddetection element 220 are enhanced.

As described above, the infrared-absorbing body is disposed above thecapacitor 230, and the heat due to infrared irradiation is transferredto the pyroelectric body 232 from the infrared-absorbing body. Since thesecond electrode (upper electrode) 236 is present in this thermalconduction path, the suppression of radiation from the second electrodewiring layer 224 connected to the second electrode 236 contributes toincreasing the efficiency of heat transfer from the infrared-absorbingbody to the pyroelectric body 232. The thermal separation properties ofthe infrared detection element 220 can thus be enhanced by merelyreducing the thermal conductivity of the second electrode wiring layer224 to a value below that of the second electrode 236.

In particular, as described hereinafter, in a case in which the secondelectrode (upper electrode) 236 is provided with a thermal conductancegreater than the thermal conductance of the first electrode (lowerelectrode) 234 in order to increase the efficiency of thermal transferfrom the infrared-absorbing body to the pyroelectric body 232, thethermal separation properties of the pyroelectric infrared detectionelement 220 can be effectively enhanced by merely reducing the thermalconductivity of the second electrode wiring layer 224 to a value belowthat of the second electrode 236. However, by furthermore reducing thethermal conductivity of the first electrode wiring layer 222 to a valuebelow that of the first electrode 234, the radiation of the heat of thepyroelectric body 232 via the first electrode 234 and the firstelectrode wiring layer 222 is further reduced, and the thermalseparation properties of the pyroelectric infrared detection element 220are therefore further enhanced.

The first electrode wiring layer 222 herein may include a firstconnecting part 222A connected to the first plug 226, and a first leadwiring part 222B extending from the first connecting part 222A andhaving a smaller width than the first connecting part 222A, as shown inFIGS. 1 and 2. In the same manner, the second electrode wiring layer 224may include a second connecting part 224A connected to the second plug228, and a second lead wiring part 224B extending from the secondconnecting part 224A and having a smaller width than the secondconnecting part 224A.

In the present embodiment, the width W22 of the second lead wiring part224B is less than the maximum length W21 of a transverse section of thesecond contact hole 254, as shown in FIG. 2. The maximum length W21 ofthe transverse section of the second contact hole 254 is the length of adiagonal when the outline of the contact hole is rectangular, and is thediameter when the outline of the contact hole is circular. In thepresent embodiment, since there is no need for the infrared-absorbinglayer to be disposed in the second contact hole 254, in contrast withthe technique of Japanese Laid-Open Patent Application Publication No.2008-232896, the size of the second contact hole 254 can be set to theminimum value for the design. Since the width W22 of the second leadwiring part 224B is less than the maximum length W21 of the transversesection of the second contact hole 254, the thermal transfercharacteristics can be reduced in proportion to the sectional area. Thethermal separation properties of the infrared detection element 220 canbe enhanced by this means as well.

In addition to the configuration described above, the width W12 of thefirst lead wiring part 222B may be less than the maximum length W11 of atransverse section of the first contact hole 252, as shown in FIG. 2.Through this configuration, the thermal transfer characteristics of thefirst lead wiring part 222B are also reduced, and the thermal separationproperties of the infrared detection element 220 can therefore befurther enhanced.

Another point of technical significance of reducing the widths W12, W22of the first and second lead wiring parts 222B, 224B is that theefficiency of absorption by the infrared-absorbing layer is enhanced.This point will be described hereinafter.

3. Overview of Pyroelectric Infrared Detector

FIG. 3 is a sectional view showing the entire pyroelectric infrareddetector 200 shown in FIG. 2. FIG. 3 schematically shows cross-sectionalviews in two different parts of the pyroelectric infrared detector 200with one part being a cross-sectional view taken along a vertical planepassing through both the first contact hole 252 and the second contacthole 254, and the other part being a cross-sectional view taken along avertical plane passing through the post 104. FIG. 4 is a partialsectional view showing the pyroelectric infrared detector 200 during themanufacturing process. In FIG. 4, the cavity 102 shown in FIG. 3 isembedded by a sacrificial layer 150. The sacrificial layer 150 ispresent from before the step of forming the support member 210 and thepyroelectric infrared detection element 220 until after this formationstep, and is removed by isotropic etching after the step of forming thepyroelectric infrared detection element 220.

As shown in FIG. 3, the base part 100 includes a substrate, e.g., asilicon substrate 110, and a spacer layer 120 formed by an insulationlayer (e.g., SiO₂) on the silicon substrate 110. The post (support part)104 is formed by etching the spacer layer 120, and is formed of SiO₂,for example. A plug 106 connected to one of the first and secondelectrode wiring layers 222, 224 may be disposed at the post (supportpart) 104. The plug 106 is connected to a row selection circuit (rowdriver) provided on the silicon substrate 110, or a read circuit forreading data from a detector via a column line. The cavity 102 is formedat the same time as the post 104 by etching the spacer layer 120. Theopen parts 102A shown in FIG. 2 are formed by pattern etching thesupport member 210.

The pyroelectric infrared detection element 220 mounted on the firstsurface 211A of the support member 210 includes a capacitor 230. Thecapacitor 230 includes a pyroelectric body 232, a first electrode (lowerelectrode) 234 connected to the lower surface of the pyroelectric body232, and a second electrode (upper electrode) 236 connected to the uppersurface of the pyroelectric body 232. The first electrode 234 mayinclude an adhesive layer 234D for increasing adhesion to a first layermember (e.g., SiO₂ support layer) 212 of the support member 210 (seeFIG. 4).

The capacitor 230 is covered by a reducing gas barrier layer 240 forsuppressing penetration of reducing gas (hydrogen, water vapor, OHgroups, methyl groups, and the like) into the capacitor 230 during stepsafter formation of the capacitor 230. The reason for providing thereducing gas barrier layer 240 is that the pyroelectric body (e.g., PZTor the like) 232 of the capacitor 230 is an oxide, and when an oxide isreduced, oxygen deficit occurs and the pyroelectric effects arecompromised.

The reducing gas barrier layer 240 includes a first barrier layer 242and a second barrier layer 244, as shown in FIG. 4. The first barrierlayer 242 can be formed by forming a layer of a metal oxide, e.g.,aluminum oxide Al₂O₃, by sputtering. Since reducing gas is not used insputtering, no reduction of the capacitor 230 occurs. The second barrierlayer 244 can be formed by forming a layer of aluminum oxide Al₂O₃, forexample, by Atomic Layer Chemical Vapor Deposition (ALCVD), for example.Common CVD (Chemical Vapor Deposition) methods use reducing gas, but thecapacitor 230 is isolated from the reducing gas by the first barrierlayer 242.

The total layer thickness of the reducing gas barrier layer 240 hereinis 50 to 70 nm, e.g., 60 nm. At this time, the layer thickness of thefirst barrier layer 242 formed by CVD is greater than that of the secondbarrier layer 244 formed by Atomic Layer Chemical Vapor Deposition(ALCVD), and is 35 to 65 nm, e.g., 40 nm, at minimum. In contrast, thelayer thickness of the second barrier layer 244 formed by Atomic LayerChemical Vapor Deposition (ALCVD) can be reduced; for example, a layerof aluminum oxide Al₂O₃ is formed having a thickness of 5 to 30 nm,e.g., 20 nm. Atomic Layer Chemical Vapor Deposition (ALCVD) hasexcellent embedding characteristics in comparison with sputtering andother methods, and can therefore be adapted for miniaturization, and thereducing gas barrier properties can be increased by the first and secondbarrier layers 242, 244. The first barrier layer 242 formed bysputtering is not precise in comparison with the second barrier layer244, but this aspect contributes to lowering the heat transfer ratethereof, and dissipation of heat from the capacitor 230 can therefore beprevented.

An interlayer insulation layer 250 is formed on the reducing gas barrierlayer 240. Hydrogen gas, water vapor, or other reducing gas usually isformed when the starting material gas (TEOS) of the interlayerinsulation layer 250 chemically reacts. The reducing gas barrier layer240 provided on the periphery of the capacitor 230 protects thecapacitor 230 from the reducing gas that occurs during formation of theinterlayer insulation layer 250.

The first electrode (lower electrode) wiring layer 222 and secondelectrode (upper electrode) wiring layer 224 shown in FIGS. 1 and 2 aswell are disposed on the interlayer insulation layer 250. A firstcontact hole 252 and second contact hole 254 are formed in advance inthe interlayer insulation layer 250 before formation of the electrodewiring. At this time, a contact hole is formed in the same manner in thereducing gas barrier layer 240 as well. The first electrode (lowerelectrode) 234 and the first electrode wiring layer 222 are madecontinuous by a first plug 226 embedded in the first contact hole 252.The second electrode (upper electrode) 236 and the second electrodewiring layer 224 are made continuous in the same manner by a second plug228 embedded in the second contact hole 254.

When the interlayer insulation layer 250 is not present in thisarrangement, during pattern etching of the first electrode (lowerelectrode) wiring layer 222 and the second electrode (upper electrode)wiring layer 224, the second barrier layer 244 of the reducing gasbarrier layer 240 beneath is etched, and the barrier properties thereofare reduced. The interlayer insulation layer 250 is necessary forensuring the barrier properties of the first reducing gas barrier layer240.

The interlayer insulation layer 250 preferably has a low hydrogencontent. The interlayer insulation layer 250 is therefore degassed byannealing. The hydrogen content of the interlayer insulation layer 250is thereby made lower than that of a passivation layer 260 for coveringthe first and second electrode wiring layers 222, 224.

Since the reducing gas barrier layer 240 at the top of the capacitor 230is devoid of contact holes and closed when the interlayer insulationlayer 250 is formed, the reducing gas during formation of the interlayerinsulation layer 250 does not penetrate into the capacitor 230. However,the barrier properties decline after the contact hole is formed in thereducing gas barrier layer 240. As an example of a technique forpreventing this phenomenon, the first and second plugs 226, 228 areformed by a plurality of layers 228A, 228B (only the second plug 228 isshown in FIG. 4), as shown in FIG. 4, and a barrier metal layer is usedin the first layer 228A. Reducing gas barrier properties are ensured bythe barrier metal of the first layer 228A. Highly diffusible metals suchas titanium Ti are not preferred as the barrier metal of the first layer228A, and titanium aluminum nitride TiAlN, which has minimaldiffusibility and high reducing gas barrier properties, can be used. Areducing gas barrier layer 290 may be additionally provided so as tosurround at least the second plug 228 as shown in FIG. 5, as a methodfor stopping the penetration of reducing gas from the contact hole. Thisreducing gas barrier layer 290 may also serve as the barrier metal 228Aof the second plug 228, or the barrier metal 228A may be removed. Thereducing gas barrier layer 290 may also coat the first plug 226.

The SiO₂ or SiN passivation layer 260 is provided so as to cover thefirst and second electrode wiring layers 222, 224. An infrared-absorbingbody (one example of a light-absorbing member) 270 is provided on thepassivation layer 260 above at least the capacitor 230. The passivationlayer 260 is also formed of SiO₂ or SiN, but is preferably formed of adifferent type of material which has a high etching selection ratio withrespect to the passivation layer 260 below, due to the need for patternetching of the infrared-absorbing body 270. Infrared rays are incidenton the infrared-absorbing body 270 from the direction of the arrow inFIG. 3, and the infrared-absorbing body 270 evolves heat in accordancewith the amount of infrared rays absorbed. Thus, the light incidentdirection is defined as a direction generally perpendicular to thesupport member 210 as shown by the arrow in FIG. 3. This heat istransmitted to the pyroelectric body 232, whereby the amount ofspontaneous polarization of the capacitor 230 varies according to theheat, and the infrared rays can be detected by detecting the charge dueto the spontaneous polarization.

Even when reducing gas is generated during CVD formation of thepassivation layer 260 or the infrared-absorbing body 270, the capacitor230 is protected by the first reducing gas barrier layer 240 and thebarrier metals in the first and second plugs 226, 228.

A reducing gas barrier layer 280 is provided so as to cover the externalsurface of the infrared detector 200 which includes theinfrared-absorbing body 270. The reducing gas barrier layer 280 must beformed with a smaller thickness than the reducing gas barrier layer 240,for example, in order to increase the transmittance of infrared rays (inthe wavelength spectrum of 8 to 14 μm) incident on theinfrared-absorbing body 270. For this purpose, Atomic Layer ChemicalVapor Deposition (ALCVD) is used, which is capable of adjusting thelayer thickness at a level corresponding to the size of an atom. Thereason for this is that the layer formed by a common CVD method is toothick, and infrared transmittance is adversely affected. In the presentembodiment, a layer of aluminum oxide Al₂O₃, for example, is formedhaving a thickness of 10 to 50 nm, e.g., 20 nm. As described above,Atomic Layer Chemical Vapor Deposition (ALCVD) has excellent embeddingcharacteristics in comparison with sputtering and other methods, and istherefore adapted to miniaturization, a precise layer can be formed atthe atomic level, and reducing gas barrier properties can be increasedeven in a thin layer.

On the side of the base part 100, an etching stop layer 130 for useduring isotropic etching of the sacrificial layer 150 (see FIG. 4)embedded in the cavity 102 in the process of manufacturing thepyroelectric infrared detector 200 is formed on a wall part for definingthe cavity 102, i.e., a side wall 104A and a bottom wall 110A fordefining the cavity. An etching stop layer 140 is formed in the samemanner on a lower surface (upper surface of the sacrificial layer 150)of the support member 210. In the present embodiment, the reducing gasbarrier layer 280 is formed of the same material as the etching stoplayers 130, 140. In other words, the etching stop layers 130, 140 alsohave reducing gas barrier properties. The etching stop layers 130, 140are also formed by forming layers of aluminum oxide Al₂O₃ at a thicknessof 20 to 50 nm by Atomic Layer Chemical Vapor Deposition (ALCVD).

Since the etching stop layer 130 has reducing gas barrier properties,when the sacrificial layer 150 is isotropically etched by hydrofluoricacid in a reductive atmosphere, it is possible to keep the reducing gasfrom passing through the support member 210 and penetrating into thecapacitor 230. Since the etching stop layer 140 for covering the basepart 100 has reducing gas barrier properties, it is possible to keep thetransistors or wiring of the circuit in the base part 100 from beingreduced and degraded.

4. Structure of Support Member

As shown in FIG. 3, the support part 104, the support member 210, andthe infrared detection element 220 are laminated on the base part 100 ina first direction D1 from the bottom layer to the top layer. The supportmember 210 mounts the infrared detection element 220 via the adhesivelayer 234D on the side of the first surface 211A, and the side of thesecond surface 211B faces the cavity 102. The adhesive layer 234Dconstitutes a portion (bottom layer) of the infrared detection element220.

As shown in FIG. 5, the support member 210 has the first layer member212 on the side of the first surface adjacent to at least the adhesivelayer 234D as an insulation layer, e.g., a SiO₂ support layer. The SiO₂support layer (first layer member) 212 has a smaller hydrogen contentthan the post (support part) 104, for example, which is another SiO₂layer positioned further in a second direction D2 than the SiO₂ supportlayer (first layer member) 212, where the second direction D2 is theopposite direction from the first direction D1 shown in FIG. 3. This isaccomplished by reducing the content of hydrogen or moisture in thelayer by increasing the O₂ flow rate during CVD layer formation to anamount greater than that used during normal CVD for an interlayerinsulation layer. The SiO₂ support layer (first layer member) 212 isthereby provided with a lower moisture content than the post (supportpart) 104, for example, which is an SiO₂ layer having a differenthydrogen content.

When the moisture content is small in the SiO₂ support layer (firstlayer member) 212 which is the uppermost layer of the support member 210adjacent to the adhesive layer 234D, reducing gas (hydrogen, watervapor) can be prevented from forming from the SiO₂ support layer (firstlayer member) 212 as such even when the SiO₂ support layer is exposed tohigh temperatures by heat treatment after formation of the pyroelectricbody 232. Reductive species can thus be prevented from penetrating intothe pyroelectric body 232 of the capacitor 230 from directly below (onthe side of the support member 210) the capacitor 230, and oxygendeficit in the pyroelectric body 232 can be suppressed.

Reductive species can also form from moisture of the post (support part)104, for example, as another SiO₂ layer positioned further in the seconddirection D2 than the SiO₂ support layer (first layer member) 212, butbecause the post (support part) 104 is separated from the capacitor 230,the effect thereof is less than that of the SiO₂ support layer (firstlayer member) 212. However, since reductive species can also form frommoisture of the post (support part) 104, a layer having reducing gasbarrier properties is preferably formed in advance in the support member210 positioned further in the second direction D2 than the SiO₂ supportlayer (first layer member) 212. This aspect is described below in themore specific description of the structure of the support member 210.

The support member 210 may be formed by laminating the SiO₂ supportlayer (first layer member) 212, a middle layer (second layer member)214, and another SiO₂ layer (third layer member) 216 as shown in FIG. 4,in the second direction D2 shown in FIG. 3.

In other words, in the present embodiment, the support member 210, inwhich curvature occurs when a single material is used, is formed bylaminating a plurality of different types of materials. Specifically,the first and third layer members 212, 216 may be formed of oxide layers(SiO₂), and the second layer member 214 as the middle layer may beformed of a nitride layer (e.g., Si₃N₄).

The residual compression stress, for example, that occurs in the firstlayer member 212 and third layer member 216, for example, and theresidual tensile stress that occurs in the second layer member 214 aredirected so as to cancel each other out. The residual stress in thesupport member 210 as a whole can thereby be further reduced oreliminated. In particular, the strong residual stress of the nitridelayer of the second layer member 214 is cancelled out by the oppositelydirected residual stress of two layers of oxide layers above and belowwhich constitute the first and third layer members 212, 216, and it ispossible to reduce stress that causes curvature in the support member210. Curvature-reducing effects are obtained even when the supportmember 210 is formed by two layers which include an oxide layer (SiO₂)adjacent to the adhesive layer 234D, and a nitride layer (e.g., Si₃N₄).Since curvature can be prevented by forming the support member 210 bythe method disclosed in Japanese Patent Application Publication No.2010-109035, for example, the support member 210 may not necessarilyhave a laminate structure, and may be formed by an SiO₂ layer or othersingle insulation layer, for example.

The nitride layer (e.g., Si₃N₄) for forming the second layer member 214has reducing gas barrier properties. The support member 210 can therebyalso be provided with the function of blocking reductive obstructivefactors from penetrating from the side of the support member 210 to thepyroelectric body 232 of the capacitor 230. The penetration of reductivespecies (hydrogen, water vapor) in the third layer member 216 into thepyroelectric body 232 can therefore be suppressed by the second layermember 214 having reducing gas barrier properties, even when the thirdlayer member 216 positioned further in the second direction D2 of FIG. 3than the second layer member 214 is another SiO₂ layer having a greaterhydrogen content than the SiO₂ support layer (first layer member) 212.

5. Structure of Capacitor 5.1 Thermal Conductance

FIG. 6 is a simplified sectional view showing the relevant parts of thepresent embodiment. As described above, the capacitor 230 includes apyroelectric body 232 between the first electrode (lower electrode) 234and the second electrode (upper electrode) 236. In the capacitor 230,infrared rays can be detected by utilizing a change (pyroelectric effector pyroelectronic effect) in the amount of spontaneous polarization ofthe pyroelectric body 232 according to the light intensity (temperature)of the incident infrared rays. In the present embodiment, the incidentinfrared rays are absorbed by the infrared-absorbing body 270, heat isevolved by the infrared-absorbing body 270, and the heat evolved by theinfrared-absorbing body 270 is transmitted via a solid heat transferpath between the infrared-absorbing body 270 and the pyroelectric body232.

In the capacitor 230 of the present embodiment, the thermal conductanceG1 of the first electrode (lower electrode) 234 adjacent to the supportmember 210 is less than the thermal conductance G2 of the secondelectrode (upper electrode) 236. Through this configuration, the heatcaused by the infrared rays is readily transmitted to the pyroelectricbody 232 via the second electrode (upper electrode) 236, the heat of thepyroelectric body 232 does not readily escape to the support member 210via the first electrode (lower electrode) 234, and the signalsensitivity of the infrared detection element 220 is enhanced. Since thethermal conductivity of the second electrode wiring layer 224electrically connected to the second electrode 236 is low, as describedabove, the thermal separation properties of the pyroelectric infrareddetector 200 are enhanced.

The structure of the capacitor 230 having the characteristics describedabove will be described in further detail with reference to FIG. 6.First, the thickness T1 of the first electrode (lower electrode) 234 isgreater than that of the second electrode (upper electrode) 236 (T1>T2).The thermal conductance G1 of the first electrode (lower electrode) 234is such that G1=λ1/T1, where λ1 is the thermal conductivity of the firstelectrode (lower electrode) 234. The thermal conductance G2 of thesecond electrode (upper electrode) 236 is such that G2=λ2/T2, where λ2is the thermal conductivity of the second electrode (upper electrode)236.

In order to obtain a thermal conductance relationship of G1<G2, when thefirst and second electrodes 234, 236 are both formed of the same singlematerial, such as platinum Pt or iridium Ir, then λ1=λ2, and T1>T2 fromFIG. 6. The relationship G1<G2 can therefore be satisfied.

A case in which the first and second electrodes 234, 236 are each formedof the same material will first be considered. In the capacitor 230, inorder for the crystal direction of the pyroelectric body 232 to bealigned, it is necessary to align the crystal lattice level of theboundary of the lower layer on which the pyroelectric body 232 is formedwith the first electrode 234. In other words, although the firstelectrode 234 has the function of a crystal seed layer, platinum Pt hasstrong self-orienting properties and is therefore preferred as the firstelectrode 234. Iridium Ir is also suitable as a seed layer material.

In the second electrode (upper electrode) 236, the crystal orientationsare preferably continuously related from the first electrode 234 throughthe pyroelectric body 232 and the second electrode 236, without breakingdown the crystal properties of the pyroelectric body 232. The secondelectrode 236 is therefore preferably formed of the same material as thefirst electrode 234.

When the second electrode 236 is thus formed by the same material, e.g.,Pt, Ir, or another metal, as the first electrode 234, the upper surfaceof the second electrode 236 can be used as a reflective surface. In thiscase, as shown in FIG. 6, the distance L from the top surface of theinfrared-absorbing body 270 to the top surface of the second electrode236 is preferably λ/4 (where λ is the detection wavelength of infraredrays). Through this configuration, multiple reflection of infrared raysof the detection wavelength λ occurs between the top surface of theinfrared-absorbing body 270 and the top surface of the second electrode236, and infrared rays of the detection wavelength λ can therefore beefficiently absorbed by the infrared-absorbing body 270.

5.2 Electrode Multilayer Structure

The structure of the capacitor 230 of the present embodiment shown inFIG. 6 will next be described. In the capacitor 230 shown in FIG. 6, thepreferred orientation directions of the pyroelectric body 232, the firstelectrode 234, and the second electrode 236 are aligned with the (111)orientation, for example. Through a preferred orientation in the (111)plane direction, the orientation rate of (111) orientation with respectto other plane directions is controlled to 90% or higher, for example.The (100) orientation or other orientation is more preferred than the(111) orientation in order to increase the pyroelectric coefficient, butthe (111) orientation is used so as to make polarization easy to controlwith respect to the applied field direction. However, the preferredorientation direction is not limited to this configuration.

The first electrode 234 may include, in order from the support member210, an orientation control layer (e.g., Ir) 234A for controlling theorientation so as to give the first electrode 234 a preferredorientation in the (111) plane, for example, a first reducing gasbarrier layer (e.g., IrOx) 234B, and a preferentially-oriented seedlayer (e.g., Pt) 234C.

The second electrode 236 may include, in order from the pyroelectricbody 232, an orientation alignment layer (e.g., Pt) 236A in which thecrystal alignment is aligned with the pyroelectric body 232, a secondreducing gas barrier layer (e.g., IrOx) 236B, and a low-resistance layer(e.g., Ir) 236C for lowering the resistance of the bonded surface withthe second plug 228 connected to the second electrode 236.

The first and second electrodes 234, 236 of the capacitor 230 areprovided with a multilayer structure in the present embodiment so thatthe infrared detection element 220 is processed with minimal damage andwithout reducing the capability thereof despite the small heat capacitythereof, the crystal lattice levels are aligned at each boundary, andthe pyroelectric body (oxide) 232 is isolated from reducing gas evenwhen the periphery of the capacitor 230 is exposed to a reductiveatmosphere during manufacturing or use.

The pyroelectric body 232 is formed by growing a crystal of PZT (leadzirconate titanate: generic name for Pb(Zr, Ti)O₃), PZTN (generic namefor the substance obtained by adding Nb to PZT), or the like with apreferred orientation in the (111) plane direction, for example. The useof PZTN is preferred, because even a thin layer is not readily reduced,and oxygen deficit can be suppressed. In order to obtain directionalcrystallization of the pyroelectric body 232, directionalcrystallization is performed from the stage of forming the firstelectrode 234 as the layer under the pyroelectric body 232.

The Ir layer 234A for functioning as an orientation control layer istherefore formed on the lower electrode 234 by sputtering. A titaniumaluminum nitride (TiAlN) layer or a titanium nitride (TiN) layer, forexample, as the adhesive layer 234D may also be formed under theorientation control layer 234A, as shown in FIG. 6. Such a layer isformed so that adhesion can be maintained with the SiO₂ of the SiO₂support layer (first layer member) 212, which is the top layer of thesupport member 210. Titanium (Ti) may also be applied as this type ofadhesive layer 234D, but a highly diffusible metal such as titanium (Ti)is not preferred, and titanium aluminum nitride (TiAlN) or titaniumnitride (TiN) is preferred due to the minimal diffusibility and highreducing gas barrier properties thereof.

When the first layer member 212 of the support member 210 positionedbeneath the adhesive layer 234D is formed of SiO₂, the surface roughnessRa of the SiO₂ layer on the side of the adhesive layer adjacent to thefirst electrode is preferably less than 30 nm. The smoothness of thesurface of the support member 210 on which the capacitor 230 is mountedcan thereby be maintained. When the surface on which the orientationcontrol layer 234A is formed is rough, the irregularities of the roughsurface are reflected in the growth of the crystal, and a rough surfaceis therefore not preferred.

The adhesive layer 234D may have reducing gas barrier properties.Titanium aluminum nitride (TiAlN) or titanium nitride (TiN) havereducing gas barrier properties. Reducing gas can thereby be preventedfrom penetrating into the capacitor 230 by the adhesive layer 234D whichhas reducing gas barrier properties, even when reducing gas leaks fromthe SiO₂ support layer of the support member.

The thermal conductivity of the adhesive layer 234D may be made smallerthan the thermal conductivity of the metal material for forming thefirst electrode 234. Through this configuration, the heat of thecapacitor 230 does not readily escape to the support member 210 via theadhesive layer 234D, and the signal accuracy based on the temperaturechange in the pyroelectric body 232 can be increased. As describedabove, the adhesive layer 234D having good adhesion to the SiO₂ supportlayer 212 can be titanium (Ti) based, the thermal conductivity of 21.9(W/m·K) for titanium (Ti) is markedly less than the thermal conductivityof 71.6 (W/m·K) for platinum (Pt) or the thermal conductivity of 147(W/m·K) for iridium (Ir), for example, which are metals suitable for thefirst electrode 232, and the thermal conductivity of titanium aluminumnitride (TiAlN) or titanium nitride (TiN) as nitrides of titaniumfurther decreases according to the mixture ratio of nitrogen/titanium.

The hydrolysis catalytic activity of the adhesive layer 234D ispreferably lower than the hydrolysis catalytic activity of the othermaterials of the first electrode 234. When the adhesive layer 234D haslow hydrolysis catalytic activity for reacting with moisture to formhydrogen, it is possible to suppress the formation of reducing gas byreaction with OH groups or absorbed water on the surface or in theinterlayer insulation layer beneath.

In order to isolate the pyroelectric body 232 from reductive obstructivefactors from below the capacitor 230, the IrOx layer 234B forfunctioning as a reducing gas barrier layer in the first electrode 234is used together with the second layer member (e.g., Si₃N₄) of thesupport member 210, and the etching stop layer (e.g., Al₂O₃) 140 of thesupport member 210, which exhibit reducing gas barrier properties. Thereducing gas used in degassing from the base part 100 during baking orother annealing steps of the pyroelectric body (ceramic) 232, or in theisotropic etching step of the sacrificial layer 150, for example, is areductive obstructive factor.

Evaporation vapor sometimes forms inside the capacitor 230 in the bakingstep of the pyroelectric body 232 and during other high-temperatureprocessing, but an escape route for this vapor is maintained by thefirst layer member 212 of the support member 210. In other words, inorder to allow evaporation vapor formed inside the capacitor 230 toescape, it is better to provide gas barrier properties to the secondlayer member 214 than to provide gas barrier properties to the firstlayer member 212.

The IrOx layer 234B as such has minimal crystallinity, but the IrOxlayer 234B is in a metal-metal oxide relationship with the Ir layer 234Aand thus has good compatibility therewith, and can therefore have thesame preferred orientation direction as the Ir layer 234A.

The Pt layer 234C for functioning as a seed layer in the first electrode234 is a seed layer for the preferred orientation of the pyroelectricbody 232, and has the (111) orientation. In the present embodiment, thePt layer 234C has a two-layer structure. The first Pt layer forms thebasis of the (111) orientation, microroughness is formed on the surfaceby the second Pt layer, and the Pt layer 234C thereby functions as aseed layer for preferred orientation of the pyroelectric body 232. Thepyroelectric body 232 is in the (111) orientation after the fashion ofthe seed layer 234C.

In the second electrode 236, since the boundaries of sputtered layersare physically rough, trap sites occur, and there is a risk of degradedcharacteristics, the lattice alignment is reconstructed on the crystallevel so that the crystal orientations of the first electrode 234, thepyroelectric body 232, and the second electrode 236 are continuouslyrelated.

The Pt layer 236A in the second electrode 236 is formed by sputtering,but the crystal direction of the boundary immediately after sputteringis not continuous. Therefore, an annealing process is subsequentlyperformed to re-crystallize the Pt layer 236A. In other words, the Ptlayer 236A functions as an orientation alignment layer in which thecrystal orientation is aligned with the pyroelectric body 232.

The IrOx layer 236B in the second electrode 236 functions as a barrierfor reductive degrading factors from above the capacitor 230. Since theIrOx layer 236B has a high resistance value, the Ir layer 236C in thesecond electrode 236 is used to lower the resistance value with respectto the second plug 228. The Ir layer 236C is in a metal oxide-metalrelationship with the IrOx layer 236B and thus has good compatibilitytherewith, and can therefore have the same preferred orientationdirection as the IrOx layer 236B.

In the present embodiment, the first and second electrodes 234, 236 thushave multiple layers arranged in the sequence Pt, IrOx, Ir from thepyroelectric body 232, and the materials forming the first and secondelectrodes 234, 236 are arranged symmetrically about the pyroelectricbody 232.

However, the thicknesses of each layer of the multilayer structuresforming the first and second electrodes 234, 236 are asymmetrical aboutthe pyroelectric body 232. The total thickness T1 of the first electrode234 and the total thickness T2 of the second electrode 236 satisfy therelationship (T1>T2) as also described above. The thermal conductivitiesof the Ir layer 234A, IrOx layer 234B, and Pt layer 234C of the firstelectrode 234 are designated as λ1, λ2, and λ3, respectively, and thethicknesses thereof are designated as T11, T12, and T13, respectively.The thermal conductivities of the Ir layer 236C, IrOx layer 236B, and Ptlayer 236A are also designated as λ1, λ2, and λ3, respectively, the sameas in the first electrode 234, and the thicknesses thereof aredesignated as T21, T22, and T23, respectively.

When the thermal conductances of the Ir layer 234A, IrOx layer 234B, andPt layer 234C of the first electrode 234 are designated as G11, G12, andG13, respectively, G11=λ1/T11, G12=λ2/T12, and G13=λ3/T13. When thethermal conductances of the Ir layer 236C, IrOx layer 236B, and Pt layer236A of the second electrode 236 are designated as G21, G22, and G23,respectively, G21=λ1/T21, G22=λ2/T22, and G13=λ3/T23.

Since 1/G1=(1/G11)+(1/G12)+(1/G13), the total thermal conductance G1 ofthe first electrode 234 is expressed by the equation (1) below.G1=(G11×G12×G13)/(G11×G12+G12×G13+G11×G13)   (1)

In the same manner, since 1/G2=(1/G21)+(1/G22)+(1/G23), the totalthermal conductance G2 of the second electrode 236 is expressed by theequation (2) below.G2=(G21×G22×G23)/(G21×G22+G22×G23+G21×G23)   (2)

The thicknesses of each layer of the multilayer structures forming thefirst and second electrodes 234, 236 are substantially in therelationships described below under conditions that satisfyT11+T12+T13=T1>T2=T21+T22+T23.

Ir layers 234A, 236C T11:T21=1:0.7

IrOx layers 234B, 236B T12:T22=0.3:1

Pt layers 234C, 236A T13:T23=3:1

The reasons for adopting such layer thickness relationships are asfollows. First, regarding the Ir layers 234A, 236C, since the Ir layer234A in the first electrode 234 functions as an orientation controllayer, a predetermined layer thickness is necessary in order to impartorientation properties, whereas the purpose of the Ir layer 236C of thesecond electrode 236 is to lower resistance, and lower resistance can beobtained the thinner the layer is.

Next, regarding the IrOx layers 234B, 236B, barrier properties againstreductive obstructive factors from below and above the capacitor 230 areobtained by joint use of other barrier layers (the second layer member214, the reducing gas barrier layer 240, and the etching stoplayers/reducing gas barrier layers 140, 280), and the IrOx layer 234B ofthe first electrode 234 is formed having a small thickness, but thethickness of the IrOx layer 236B of the second electrode 236 isincreased to compensate for low barrier properties in the second plug228.

Lastly, regarding the Pt layers 234C, 236A, the Pt layer 234C in thefirst electrode 234 functions as a seed layer for determining thepreferred orientation of the pyroelectric body 232, and therefore musthave a predetermined layer thickness, whereas the purpose of the Ptlayer 236A of the second electrode 236 is to function as an orientationalignment layer aligned with the orientation of the pyroelectric body232, and the Pt layer 236A may therefore be formed with a smallerthickness than the Pt layer 234C in the first electrode 234.

The thickness ratio of the Ir layer 234A, IrOx layer 234B, and Pt layer234C of the first electrode 234 is set so that T11:T12:T13=10:3:15, forexample, and the thickness ratio of the Ir layer 236C, IrOx layer 236B,and Pt layer 236A of the second electrode 236 is set so thatT21:T22:T23=7:10:5, for example.

The thermal conductivity λ3 of Pt is equal to 71.6 (W/m·K), and thethermal conductivity λ1 of Ir is equal to 147 (W/m·K), which issubstantially twice the thermal conductivity λ3 of Pt. The thermalconductivity λ2 of IrOx varies according to the temperature or theoxygen/metal ratio (O/M), but does not exceed the thermal conductivityλ1 of Ir. When the layer thickness relationships and thermalconductivity relationships described above are substituted intoEquations (1) and (2) to calculate the size relationship between G1 andG2, it is apparent that G1<G2. Thus, even when the first and secondelectrodes 234, 236 are provided with a multilayer structure as in thepresent embodiment, the expression G1<G2 is satisfied from therelationship of the thermal conductivities and layer thicknesses.

When the first electrode 234 has the adhesive layer 234D on the bondedsurface with the support member 210 as described above, the thermalconductance G1 of the first electrode 234 is reduced, and therelationship G1<G2 is easily satisfied.

Since the etching mask of the capacitor 230 degrades as etchingproceeds, the side walls of the capacitor 230 acquire a tapered shapewhich is narrower at the top and wider at the bottom as shown in FIG. 6,the more layers are added to the structure. However, since the taperangle with respect to the horizontal surface is about 80 degrees,considering that the total height of the capacitor 230 is on the orderof nanometers, the increase in surface area of the first electrode 234with respect to the second electrode 236 is small. The amount of heattransferred by the first electrode 234 can thereby be kept smaller thanthe amount of heat transferred by the second electrode 236, based on therelationship between the thermal conductance values of the first andsecond electrodes 234, 236.

5.3 Modifications of Capacitor Structure

A single-layer structure and multilayer structure are described abovefor the first and second electrodes 234, 236 of the capacitor 230, butvarious other combinations of structures are possible which produce thethermal conductance relationship G1<G2 while maintaining the function ofthe capacitor 230.

First, the Ir layer 236C of the second electrode 236 may be omitted. Thereason for this is that in this case, the object of lowering resistanceis achieved in the same manner when Ir, for example, is used as thematerial of the second plug 228. Through this configuration, since thethermal conductance G2 of the second electrode 236 is greater than inthe case shown in FIG. 6, the relationship G1<G2 is easily satisfied. Areflective surface for defining L=λ/4 shown in FIG. 6 takes the place ofthe Pt layer 236A of the second electrode 236 in this case, but amultiple reflection surface can be ensured in the same manner.

Next, the thickness of the IrOx layer 236B in the second electrode 236in FIG. 6 may be made equal to or less than the thickness of the IrOxlayer 234B in the first electrode 234. As described above, since thebarrier properties against reductive obstructive factors from below andabove the capacitor 230 are obtained by joint use of other barrierlayers (the second layer member 214, the reducing gas barrier layer 240,and the etching stop layers/reducing gas barrier layers 140, 280), whenthe reducing gas barrier properties in the second plug 228 are increasedby the configuration shown in FIG. 5, for example, there is no need forthe thickness of the IrOx layer 236B in the second electrode 236 to begreater than the thickness of the IrOx layer 234B in the first electrode234. Through this configuration, the thermal conductance G2 of thesecond electrode 236 further increases, and the relationship G1<G2 iseasier to obtain.

Next, the IrOx layer 234B in the first electrode 234 in FIG. 6 may beomitted. Crystal continuity between the Ir layer 234A and the Pt layer234C is not hindered by omission of the IrOx layer 234B, and no problemsoccur with regard to crystal orientation. When the IrOx layer 234B isomitted, the capacitor 230 has no barrier layer with respect toreductive obstructive factors from below the capacitor 230. However, thesecond layer member 214 is present in the support member 210 forsupporting the capacitor 230, and the etching stop layer 140 is presenton the lower surface of the support member 210, and when the secondlayer member 214 and the etching stop layer 140 are formed by layershaving reducing gas barrier properties, barrier properties with respectto reductive obstructive factors from below the capacitor 230 can beensured in the capacitor 230.

When the IrOx layer 234B in the first electrode 234 is omitted in thisarrangement, the thermal conductance G1 of the first electrode 234increases. It may therefore be necessary to increase the thermalconductance G2 of the second electrode 236 as well in order to obtainthe relationship G1<G2. In this case, the IrOx layer 236B in the secondelectrode 236 may be omitted, for example. Once the IrOx layer 236B isomitted, the Ir layer 236C is also no longer necessary. The reason forthis is that the Pt layer 236A functions as a low-resistance layer inplace of the Ir layer 236C. Barrier properties with respect to reductiveobstructive factors from above the capacitor 230 can be maintained bythe first reducing gas barrier layer 240 described above, the barriermetal 228A shown in FIG. 4, or the reducing gas barrier layer 290 shownin FIG. 5.

When the second electrode 236 shown in FIG. 6 is formed only by the Ptlayer 236A as described above, the first electrode 234 may be formed bythe Pt layer 234C as a single layer, by the Ir layer 234A and Pt layer234C as two layers, or by the Ir layer 234A of FIG. 6, the IrOx layer234B, and the Pt layer 234C as three layers. In any of these cases, therelationship G1<G2 can easily be obtained by making the thickness T13 ofthe Pt layer 234C of the first electrode 234 greater than the thicknessT23 of the Pt layer 236A of the second electrode 236 (T13>T23), forexample.

As described above, in the present embodiment, platinum (Pt) or iridium(Ir) is used as the material (single-layer electrode material in thecase of single-layer electrodes, and the electrode material of theuppermost layer in the case of multi-layer electrodes) for forming thefirst and second electrodes 234, 236 in the portion connected to thefirst and second plugs 226, 228. In any case, by using titanium nitride(TiN) or titanium aluminum nitride (TiAlN), for example, as the firstand second electrode wiring layers 222, 224, the thermal conductivity ofthe first and second electrode wiring layers 222, 224 can be made lowerthan the thermal conductivity of the first and second electrodes 234,236, and the thermal separation characteristics of the pyroelectricinfrared detector 200 can be improved.

6. Enhancement of Infrared Absorption Efficiency by Reflection byElectrode Surfaces

FIG. 7 is a sectional view showing a modification in which the region inwhich the infrared-absorbing layer 270 of FIG. 3 is disposed isenlarged. The enhancement of infrared absorption efficiency byreflection by the electrode surfaces in the embodiments shown in FIGS. 3and 7 will be described using FIG. 7.

A portion of the infrared rays incident from the direction of the arrowin FIG. 7 is absorbed by the infrared-absorbing layer 270 and convertedto heat, and the remainder of the infrared rays is transmitted. At thistime, in the embodiments shown in FIGS. 3 and 7, the transmittedinfrared rays are reflected on the surface of the second electrode(upper electrode) 236 and returned toward the center of theinfrared-absorbing layer 270 (R1 in FIG. 7). Through this reflection,the transmitted infrared rays are given another opportunity to beabsorbed by the infrared-absorbing layer 270, and the infraredabsorption efficiency is therefore increased.

Infrared rays are reflected not only at the second electrode (upperelectrode) 236, but also at the second electrode wiring layer 224 (R1′in FIG. 7). However, the maximum absorption occurs at different heightpoints within the infrared-absorbing layer 270 for the infrared raysreflected at the second electrode (upper electrode) 236 and the infraredrays reflected at the second electrode wiring layer 224. The infraredabsorption efficiency therefore decreases. Although the maximumabsorption of the infrared rays reflected at the second electrode (upperelectrode) 236 occurs at a constant height point when the secondelectrode wiring layer 224 is not present, the second electrode wiringlayer 224 is necessary.

Therefore, by reducing the width W22 of the second electrode wiringlayer 224 as described above, a reduction in infrared absorptionefficiency can be suppressed.

In the embodiment shown in FIG. 7, the infrared-absorbing layer 270 isdisposed also in a position opposite the second region 233B in which thefirst electrode (lower electrode) 234 is enlarged. Through thisconfiguration, the volume of the infrared-absorbing layer 270 isincreased, and not only is the amount of heat absorbed thereforeincreased, but infrared rays can also be reflected at the firstelectrode (lower electrode) 234 (R2 in FIG. 7). The amount of heatabsorbed by the infrared-absorbing layer 270 is therefore furtherincreased.

At the same time that infrared rays are reflected at the first electrode(lower electrode) 234, infrared rays are reflected by the firstelectrode wiring layer 222 (omitted in FIG. 7) as well, and the sameproblem occurs as in the second electrode. However, a reduction ininfrared absorption efficiency can be suppressed by reducing the widthW12 of the first electrode wiring layer 222 as described above.

7. Electronic Instrument

FIG. 8 shows an example of the configuration of an electronic instrumentwhich includes the pyroelectric detector or pyroelectric detectiondevice of the present embodiment. The electronic instrument includes anoptical system 400, a sensor device (pyroelectric detection device) 410,an image processor 420, a processor 430, a storage unit 440, anoperating unit 450, and a display unit 460. The electronic instrument ofthe present embodiment is not limited to the configuration shown in FIG.8, and various modifications thereof are possible, such as omitting someconstituent elements (e.g., the optical system, operating unit, displayunit, or other components) or adding other constituent elements.

The optical system 400 includes one or more lenses, for example, a driveunit for driving the lenses, and other components. Such operations asforming an image of an object on the sensor device 410 are alsoperformed. Focusing and other adjustments are also performed as needed.

The sensor device 410 is formed by arranging the pyroelectric detector200 of the present embodiment described above in two dimensions, and aplurality of row lines (word lines, scan lines) and a plurality ofcolumn lines (data lines) are provided. In addition to the opticaldetector arranged in two dimensions, the sensor device 410 may alsoinclude a row selection circuit (row driver), a read circuit for readingdata from the optical detector via the column lines, an A/D conversionunit, and other components. Image processing of an object image can beperformed by sequentially reading data from detectors arranged in twodimensions.

The image processor 420 performs image correction processing and variousother types of image processing on the basis of digital image data(pixel data) from the sensor device 410.

The processor 430 controls the electronic instrument as a whole andcontrols each block within the electronic instrument. The processor 430is realized by a CPU or the like, for example. The storage unit 440stores various types of information and functions as a work area for theprocessor 430 or the image processor 420, for example. The operatingunit 450 serves as an interface for operation of the electronicinstrument by a user, and is realized by various buttons, a GUI(graphical user interface) screen, or the like, for example. The displayunit 460 displays the image acquired by the sensor device 410, the GUIscreen, and other images, for example, and is realized by a liquidcrystal display, an organic EL display, or another type of display.

A pyroelectric detector of one cell may thus be used as an infraredsensor or other sensor, or the pyroelectric detector of one cell may bearranged along orthogonal axes in two dimensions to form the sensordevice 410, in which case a heat (light) distribution image can beprovided. This sensor device 410 can be used to form an electronicinstrument for thermography, automobile navigation, a surveillancecamera, or another application.

As shall be apparent, by using one cell or a plurality of cells ofpyroelectric detectors as a sensor, it is possible to form an analysisinstrument (measurement instrument) for analyzing (measuring) physicalinformation of an object, a security instrument for detecting fire orheat, an FA (factory automation) instrument provided in a factory or thelike, and various other electronic instruments.

FIG. 9A shows an example of the configuration of the sensor device 410shown in FIG. 10. This sensor device includes a sensor array 500, a rowselection circuit (row driver) 510, and a read circuit 520. An A/Dconversion unit 530 and a control circuit 550 may also be included. Aninfrared camera or the like used in a night vision instrument or thelike, for example, can be realized through the use of the sensor devicedescribed above.

A plurality of sensor cells is arrayed (arranged) along two axes asshown in FIG. 2, for example, in the sensor array 500. A plurality ofrow lines (word lines, scan lines) and a plurality of column lines (datalines) are also provided. The number of either the row lines or thecolumn lines may be one. In a case in which there is one row line, forexample, a plurality of sensor cells is arrayed in the direction(transverse direction) of the row line in FIG. 9A. In a case in whichthere is one column line, a plurality of sensor cells is arrayed in thedirection (longitudinal direction) of the column line.

As shown in FIG. 9B, the sensor cells of the sensor array 500 arearranged (formed) in locations corresponding to the intersectionpositions of the row lines and the column lines. For example, a sensorcell in FIG. 9B is disposed at a location corresponding to theintersection position of word line WL1 and column line DL1. Other sensorcells are arranged in the same manner.

The row selection circuit 510 is connected to one or more row lines, andselects each row line. Using a QVGA (320×240 pixels) sensor array 500(focal plane array) such as the one shown in FIG. 9B as an example, anoperation is performed for sequentially selecting (scanning) the wordlines WL0, WL1, WL2, . . . WL239. In other words, signals (wordselection signals) for selecting these word lines are outputted to thesensor array 500.

The read circuit 520 is connected to one or more column lines, and readseach column line. Using the QVGA sensor array 500 as an example, anoperation is performed for reading detection signals (detectioncurrents, detection charges) from the column lines DL0, DL1, DL2, . . .DL319.

The A/D conversion unit 530 performs processing for A/D conversion ofdetection voltages (measurement voltages, attained voltages) acquired inthe read circuit 520 into digital data. The A/D conversion unit 530 thenoutputs the A/D converted digital data DOUT. Specifically, the A/Dconversion unit 530 is provided with A/D converters corresponding toeach of the plurality of column lines. Each A/D converter performs A/Dconversion processing of the detection voltage acquired by the readcircuit 520 in the corresponding column line. A configuration may beadopted in which a single A/D converter is provided so as to correspondto a plurality of column lines, and the single A/D converter is used intime division for A/D conversion of the detection voltages of aplurality of column lines.

The control circuit 550 (timing generation circuit) generates variouscontrol signals and outputs the control signals to the row selectioncircuit 510, the read circuit 520, and the A/D conversion unit 530. Acontrol signal for charging or discharging (reset), for example, isgenerated and outputted. Alternatively, a signal for controlling thetiming of each circuit is generated and outputted.

Several embodiments are described above, but it will be readily apparentto those skilled in the art that numerous modifications can be madeherein without substantively departing from the new matter and effectsof the present invention. All such modifications are thus included inthe scope of the present invention. For example, in the specification ordrawings, terms which appear at least once together with different termsthat are broader or equivalent in meaning may be replaced with thedifferent terms in any part of the specification or drawings.

The present invention is broadly applicable to various pyroelectricdetectors (e.g., thermocouple-type elements (thermopiles), pyroelectricelements, bolometers, and the like), irrespective of the wavelength oflight detected. The pyroelectric detector or pyroelectric detectiondevice, or the electronic instrument which has the pyroelectric detectoror pyroelectric detection device, may also be applied to a flow sensoror the like for detecting the flow rate of a liquid under conditions inwhich an amount of supplied heat and an amount of heat taken in by thefluid are in equilibrium. The pyroelectric detector or pyroelectricdetection device of the present invention may be provided in place of athermocouple or the like provided to the flow sensor. The pyroelectricdetector or pyroelectric detection device of the present invention maybe provided in place of a thermocouple or the like provided to the flowsensor, and a subject other than light may be detected.

General Interpretation of Terms

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts. Finally, terms of degree such as“substantially”, “about” and “approximately” as used herein mean areasonable amount of deviation of the modified term such that the endresult is not significantly changed. For example, these terms can beconstrued as including a deviation of at least ±5% of the modified termif this deviation would not negate the meaning of the word it modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing descriptions of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

1. A pyroelectric detector comprising: a support member including afirst side and a second side opposite from the first side, with thesecond side facing a cavity; and a pyroelectric detection elementmounted on the first side of the support member, the pyroelectricdetection element including a capacitor including a first electrode, apyroelectric body and a second electrode, the first electrode beingmounted on the support member and including a first region in which thepyroelectric body is disposed and a second region extending from thefirst region, the pyroelectric body being disposed over the firstelectrode in the first region, and the second electrode being disposedover the pyroelectric body, an interlayer insulation layer covering asurface of the capacitor, and forming a first contact hole passingthrough to the first electrode in the second region, and a secondcontact hole passing through to the second electrode, a first plugembedded in the first contact hole, a second plug embedded in the secondcontact hole, a first electrode wiring layer formed on the interlayerinsulation layer and on the first side of the support member, andconnected to the first plug, and a second electrode wiring layer formedon the interlayer insulation layer and on the first side of the supportmember, and connected to the second plug, a thermal conductivity ofmaterial of the second electrode wiring layer being lower than a thermalconductivity of material of a portion of the second electrode connectedto the second plug.
 2. The pyroelectric detector according to claim 1,wherein a thermal conductivity of material of the first electrode wiringlayer is lower than a thermal conductivity of material of a portion ofthe first electrode connected to the first plug.
 3. The pyroelectricdetector according to claim 1, wherein at least one of the firstelectrode wiring layer and the second electrode wiring layer containsone of titanium nitride and titanium aluminum nitride.
 4. Thepyroelectric detector according to claim 1, wherein a thermalconductance of the second electrode is greater than a thermalconductance of the first electrode.
 5. The pyroelectric detectoraccording to claim 1, wherein the pyroelectric detection element furtherincludes a light-absorbing member disposed in a region further upstreamin a light incidence direction than the second electrode and the secondwiring layer.
 6. The pyroelectric detector according to claim 1, furthercomprising a reducing gas barrier layer disposed between the interlayerinsulation layer and the capacitor.
 7. A pyroelectric detection devicecomprising: a plurality of the pyroelectric detectors according to claim1 arranged in two dimensions along two axes.
 8. An electronic instrumentcomprising: the pyroelectric detector according to claim
 1. 9. Apyroelectric detection device comprising: a plurality of thepyroelectric detectors according to claim 2 arranged in two dimensionsalong two axes.
 10. A pyroelectric detection device comprising: aplurality of the pyroelectric detectors according to claim 3 arranged intwo dimensions along two axes.
 11. A pyroelectric detection devicecomprising: a plurality of the pyroelectric detectors according to claim4 arranged in two dimensions along two axes.
 12. The pyroelectricdetector according to claim 5, wherein the light-absorbing member coversan entire surface of the second electrode in plan view as viewed alongthe light incidence direction, and the second electrode covers an entiresurface of a first side of the pyroelectric body that is opposite from asecond side facing the first electrode.
 13. The pyroelectric detectoraccording to claim 5, wherein the light-absorbing member overlaps withthe first region of the first electrode and at least a portion of thesecond region of the first electrode in plan view as viewed along thelight incidence direction.
 14. The pyroelectric detector according toclaim 5, wherein the first electrode wiring layer includes a firstconnecting part connected to the first plug, and a first lead wiringpart extending from the first connecting part and having a width smallerthan a width of the first connecting part, the second electrode wiringlayer includes a second connecting part connected to the second plug,and a second lead wiring part extending from the second connecting partand having a width smaller than a width of the second connecting part,and the width of the second lead wiring part is less than a maximumlength in a transverse-cross section of the second contact hole.
 15. Apyroelectric detection device comprising: a plurality of thepyroelectric detectors according to claim 5 arranged in two dimensionsalong two axes.
 16. An electronic instrument comprising: thepyroelectric detection device according to claim
 7. 17. A pyroelectricdetection device comprising: a plurality of the pyroelectric detectorsaccording to claim 12 arranged in two dimensions along two axes.
 18. Apyroelectric detection device comprising: a plurality of thepyroelectric detectors according to claim 13 arranged in two dimensionsalong two axes.
 19. The pyroelectric detector according to claim 14,wherein the width of the first lead wiring part is less than the maximumlength in a transverse cross-section of the first contact hole.
 20. Apyroelectric detection device comprising: a plurality of thepyroelectric detectors according to claim 14 arranged in two dimensionsalong two axes.